How to WP_Query filter by a date field?

Hi, I’ve been using your plugin on a few sites and I’m really happy with its ease of use. But I am stuck on one thing.

I have a date field which seems to store the date in the following format: YYYY-MM-DD

Now I am running a custom query and I need to retrieve all posts AFTER a certain date. Do you know if this is possible? Here is the type of query I’m trying to use:

$args = array(
	'posts_per_page' => -1,
	'meta_query' => array(
		array(
			'key' => 'date_of_workshop',
			'value' => '2014-05-10',
			'compare' => '>=',
			'type' => 'DATE'
		)
	)
);

I’ve tried to use different types such as NUMERIC & DATETIME, as well as changing the value to ‘Y-m-d H:i:s’ but I’ve had no luck.

Is there a native WP way to do this or will I a) have to retrieve ALL posts and filter by the date field, or b) run a manual SQL query?|

Thanks for all your effort!

John..

https://wordpress.org/plugins/custom-field-suite/